This is an old trick that I need to note, because I always forget the exact syntax.
It creates a SSH tunnel on a server where you have access, and you can use this tunnel to connect to the internet through that server.
Knowing that you can rent a cheap VPS in the USA for a couple of dollars, it can be practical for instances when you want to watch videos that can only be accessed there.
So there are three steps:
1) Create the SSH tunnel
ssh -D 5555 yourlogin@yourserver
3) Check that you are really using that tunnel
That site is nice because it gives your IP and its geographical position: